The kernel is trying to bring up interface DB88FXX81, instead of eth0.

That was one issue, i had an extra ':' on the config line. The right one,bootcmd=run boottftp;setenv bootargs $(console) $(bootargs_nfs) ip=$(ipaddr):$(serverip)$(bootargs_end);bootm 0x2000000

The other issue, was that bootargs was printenv,bootargs=console=ttyS0,115200 mtdparts=nand_mtd:0x100000@0(uboot)ro,0x0@0x100000(uImage),0x1ff00000@0x100000(rootfs)rw root=/dev/nfs rw nfsroot=$(serverip):/tftpboot/rootfs ip=192.168.0.35:192.168.0.20::::DB88FXX81:eth0:none

bootargs did not automatically translate $(serverip) when setting nfsroot, so i hardcoded the value and it boots fine now.